EDC exposures for reproductive-aged women tied to socioeconomic status
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Key takeaways:
- Exposure to most types of EDCs decreased for pregnant and reproductive-aged women in recent years.
- Levels of two types of polyaromatic hydrocarbons rose in 2013-2016 compared with 2001-2004.
BOSTON — Pregnant and reproductive-aged women have had recent declines in exposure to most endocrine-disrupting chemicals, though women with a lower socioeconomic status are exposed to higher chemical levels, according to a speaker.
In an analysis of data from the National Health and Nutrition Examination Survey from 1999 to 2020, researchers examined trends in endocrine-disrupting chemical (EDC) exposure for pregnant women as well as women aged 14 to 44 years. Additionally, exposure to EDCs was assessed by socioeconomic status, where researchers found women with a lower socioeconomic status had higher urinary and serum EDC levels than women in higher groups.
“Our results provide new insights into the trends of exposure to thyroidal EDCs in reproductive-aged and pregnant women in the U.S.,” Cheng Han, MD, a researcher in the section of endocrinology, diabetes and nutrition at the Boston University Chobanian & Avedisian School of Medicine, said during a presentation at ENDO 2024. “Using linear regression models, we found significant associations between socioeconomic status and the levels of EDCs exposure. We discovered that most EDCs [levels] are lower in high-income women.”
Researchers obtained data from 10 consecutive NHANES cycles from 1999 to 2020. Urine and serum levels were collected from 2,525 pregnant women and 25,320 reproductive-aged women to assess exposure levels to EDCs known to affect thyroid function. Researchers analyzed changes in EDC exposure among both groups of women during the study.
“With thyroid disorder prevalent among women of reproductive age, thyroid dysfunction during pregnancy is not uncommon,” Han said. “Both clinical thyroid disruption and subclinical thyroid disruption has been associated with a spectrum of poor obstetric outcomes. In light of multiple reports of EDCs affecting thyroid function, it is even more important to study their impact on sensitive populations.”
EDC exposure changes
Exposure to most EDCs declined for both groups during the study. Reproductive-aged women were exposed to lower levels of perchlorate, nitrate, thiocyanate, six polyaromatic hydrocarbons, eight phthalate and plasticizers, six personal care product chemicals and metabolites, five organochlorides and four per- and polyfluoroalkyl substances (PFAS) during the study. Exposure to dioxins dropped in 2003-2006 and 2007-2010 from 1999-2002 before rising again in 2011-2012. Reproductive-aged women had higher levels of two polyaromatic hydrocarbons in 2013-2016 compared with 2001-2004.
Among pregnant women, declines were seen in exposure to one type of polyaromatic hydrocarbon, five organochlorides, three personal care products and metabolites, eight phthalates and plasticizers and four PFAS during the study. Similar to reproductive-aged women, pregnant women had an increase in exposure to two types of polyaromatic hydrocarbons in 2013-2016 compared with 2001-2004. Also similar to reproductive-aged women, exposure to eight dioxins increased in 2011-2012 after declining in 2003-2006 and 2007-2010 from 1999-2002 levels. Pregnant women had no change in perchlorate, nitrate and thiocyanate levels.
Socioeconomic disparities
Researchers assessed associations between exposure to EDCs and socioeconomic status for both groups, with women divided into tertiles based on socioeconomic status. For reproductive-aged women, those in the highest tertile for socioeconomic status were exposed to lower levels of nitrate, thiocyanate, 10 types of polyaromatic hydrocarbons, three types of phthalates, three types of personal care product metabolites, two types of organochlorides and two types of dioxins than women in the lowest socioeconomic status group. Conversely, women in the highest tertiles were exposed to higher levels of three types of personal care product metabolites, three types of phytoestrogen and four types of PFAS than women in the low socioeconomic status group.
Pregnant women in the highest tertile for socioeconomic status were exposed to lower levels of thiocyanate, eight types of polyaromatic hydrocarbons, four types of phthalates and two types of personal care product metabolites than those in the lowest tertile. Exposure to methyl parabens, a type of the personal care product metabolite, was higher for women in the highest socioeconomic status group than those in the lowest tertile.
Han said the findings of the study should be used to inform future policy decisions on EDCs and future scientific research.
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Han C, et al. OR26-03. Presented at: ENDO annual meeting; June 1-4, 2024; Boston.
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